Chinese scientists of Fudan University Shanghai, China, found a way to avoid plunging battery kinetics. At freezing temperatures common lithium-ion batteries tend to lose their capacity; but with their new designed battery system, low temperatures do not pose a problem any longer.
By using “non-graphitizable” or “hard” carbon the researchers found out that it can exhibit fast intercalation kinetics of lithium ions. These ions normally migrate from the cathode through an electrolyte to the anode. The anodic material, most of the times graphite, can incorporate prestored lithium. If this is the case, cell life can be extended and is able to provide faster charge/discharge kinetics due to the leveling out of the incoming lithium ions. This process, though, is very expensive. That is why Yonggang Wang and his team favor different methods.
His team introduced a lithium-rich vanadium phosphate electrode both for lithiation and normal battery operation instead of the usually used extra lithium electrode. The lithium-ions lost by the cathode get intercalated and stored in the anode in the first charging process. The lithium-reduced vanadium phosphate cathode and relithiated hard-carbon anode got combined, forming a working lithium-ion battery system. This innovation guarantees higher power and a long cycle life. On top of that it keeps about two-thirds of its capacity at low temperatures (minus 40 degrees Celcius).
Although the electrolyte loses conductivity under extremely cold conditions, this system can provide one of the best performances once more research has been done.
Source: Wiley Online Library